<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <button @click="fn">按钮1</button>
    <button @click.once="fn">按钮2</button>

  </div>
  <script src="lib/vue.js"></script>
  <script>
    new Vue({
      el: '#app',
      data: {

      },
      methods: {
        fn () {
          console.log('按钮被点击了');
        }
      }
    })
  </script>
</body>
</html>